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China Foundry 2024年第4期21卷 360-368页

作者： Jia-ping Fu can-xu {1. Guo-fa Mi Yuan Liu School of Materials Science and Engineering Henan Polytechnic UniversityJiaozuo 454100HenanChina School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China

Diamond/aluminium composites have attracted attention in the field of thermal management of electronic packaging for their excellent *** order to solve the interfacial problem between diamond and aluminium,a novel process combining pressure infiltration with vacuum-assisted technology was proposed to prepare diamond/aluminum *** effect of diamond particle size on the microstructure and properties of the diamond/Al-1.Si composites was *** results show that the diamond/Al-1.Si composites exhibit high relative density and a uniform *** thermal conductivity and coefficient of thermal expansion increase with increasing particle size,while the bending strength exhibits the opposite *** the average diamond particle size increases from 45μm to 425μm,the thermal conductivity of the composites increases from 455 W·m^(-1.·K^(-1.to 71. W·m^(-1.·K^(-1.and the coefficient of thermal expansion increases from 4.97×1.^(-6)K^(-1.to 6.72×1.^(-6)K^(-1.,while the bending strength decreases from 353 MPa to 246 *** research demonstrates that high-quality composites can be prepared by the vacuum-assisted pressure infiltration process and the thermal conductivity of the composites can be effectively improved by increasing the diamond particle size.

关键词： diamond/aluminum composites thermal conductivity electronic packaging vacuum-assisted pressure infiltration

Highly Hydrolysis-Resistant Polyimide Fibers Prepared by Thermal Crosslinking with Inherent Carboxyl Groups

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Chinese Journal of Polymer Science 2024年第2期42卷 247-255,I0010页

作者： can-can Zhang Jun-Long Yang Ya-Jiang Huang Guang-Xian Li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering of ChinaSichuan UniversityChengdu610065China

Easy hydrolysis in alkaline environments limits the use of polyimide fibers in environmental protection. The hydrolysis resistance levels of polyimide fibers can be improved by crosslinking of the macromolecular chains. In this work, crosslinked polyimide fibers(CPI fibers) were produced by intrinsic carboxyl decarboxylation for the first time. The thermal stability of the polyimide fibers containing the intrinsic carboxyl groups(PIC fibers) was studied, and the temperature of the decarboxylation-crosslinking reaction was determined to be 450 ℃. The PIC fibers were hotdrawn to initiate thermal crosslinking of the carboxyl groups and molecular chain orientation at high temperature. The CPI fibers had high tensile strengths(0.72-1.46 GPa) and compressive strengths(401.604 MPa). The oriented macromolecules and chemically crosslinked structure improved the tightness of the molecular chains and endowed the CPI fibers with excellent hydrolytic resistance. The CPI-50 fiber did not dissolve in a 0.5 wt% NaOH solution during heating at 90 ℃ for 1. h, and the tensile strength retention reached 87% when treated in 0.5 wt% NaOH solutions at 90 ℃ for 1.h, providing a guarantee for its application in alkaline corrosive environments.

关键词： Polyimide Carboxyl group Crosslinking Hydrolysis-resistance

Highly Improved Creep Resistance in Polypropylene Through Thermally Reduced Graphene Oxide and Its Creep Lifetime Prediction

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Chinese Journal of Polymer Science 2024年第2期42卷 256-266,I0010页

Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. This structural feature causes chain slippage in PP under stress,significantly constraining its service lifetime. In this study, thermally reduced graphene oxide(TrGO) nanosheets were incorporated into the PP matrix, yielding a nanocomposite with exceptional creep resistance performance. Results demonstrated that at a stress of 25 MPa, a 2.0 wt% TrGO content could enhance the creep failure lifetime of PP by 21.5 times compared to neat PP. Rheology, transmission electron microscopy(TEM),and scanning electron microscopy(SEM) characterization techniques were employed to analyze the mechanism of TrGO's influence on PP's creep behavior. It was observed that when TrGO content exceeded 1.0 wt%, an effective particle network structure formed within the PP matrix. This homogeneously dispersed TrGO-formed particle network structure restricted the migration and rearrangement of PP molecular chains, enabling prolonged stress resistance without structural failure. By combining the time-strain superposition method with the critical failure strain as a criterion, generalized creep compliance curves for PP and its composites were established, facilitating the prediction of material creep failure lifetimes, with a strong agreement between experimental and predicted lifetime values. This research proposes a novel strategy aimed at developing polypropylene materials and products with enhanced long-term stability and durability, thus extending service life, reducing failure risk, and broadening their potential across various application domains.

关键词： Thermally reduced graphene oxide Polypropylene Creep failure and lifetime prediction

In-situ electrochemical study on the eff ects of Fe(Ⅲ)on kinetics of pyrite acidic pressure oxidation

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Acta Geochimica 2024年第4期43卷 814-825页

作者： Yu Zhang can Cui Sen Lin Heping Li Lian Yang Yadian Xie Hailiang Hu Lingyun {1. Huanjiang Wang Chunyan Li School of Chemical Engineering Guizhou Minzu UniversityGuiyang 550025China Key Laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

Fe(Ⅲ)has been proved to be a more eff ective oxidant than dissolved oxygen at ambient temperature,however,the role of Fe(Ⅲ)in pyrite acidic pressure oxidation was rarely discussed so *** this paper,in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation *** results illustrated that increasing Fe(Ⅲ)concentrations led to raising in redox potential of the solution,and decreased passivation of pyrite caused by deposition of elemental *** of Fe(Ⅲ)at pyrite surface was a fast reaction with low activation energy,it was only slightly promoted by rising ***,the oxidation rate of pyrite at all investigated Fe(Ⅲ)concentrations increased obviously with rising temperatures,the anodic reaction was the rate-limiting step in the overall *** energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(Ⅲ)concentration was increased from 0.05 to 0.50 g/L,showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(Ⅲ)concentrations,while,it gradually turned to be diffusion control with increasing Fe(Ⅲ)concentrations.

关键词： Pyrite Pressure oxidation Fe(Ⅲ) In-situ electrochemistry Hydrothermal experiment

Mitochondrial targeting sequence of magnetoreceptor MagR:More than just targeting

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Zoological Research 2024年第3期45卷 468-477页

作者： Yanqi Zhang Peng Zhang Junjun Wang Jing Zhang Tianyang Tong Xiujuan zhou Yajie zhou Mengke Wei Chuanlin Feng Jinqian Li Xin Zhang can Xie Tiantian Cai High Magnetic Field Laboratory Hefei Institutes of Physical ScienceChinese Academy of SciencesHefeiAnhui 230031China University of Science and Technology of China HefeiAnhui 230026China Department of Anatomy School of Basic MedicineAnhui Medical UniversityHefeiAnhui 230032China Institutes of Physical Science and Information Technology Anhui UniversityHefeiAnhui 230039China Key Laboratory of Tropical Translational Medicine of Ministry of Education NHC Key Laboratory of Tropical Disease ControlSchool of Tropical Medicine and The Second Affiliated HospitalHainan Medical UniversityHaikouHainan 571199China International Magnetobiology Frontier Research Center Science IslandHefeiAnhui 230031China Institute of Quantum Sensing Zhejiang UniversityHangzhouZhejiang 310027China

Iron-sulfur clusters(ISC)are essential cofactors for proteins involved in various biological processes,such as electron transport,biosynthetic reactions,DNA repair,and gene expression *** assembly protein IscA1.or MagR)is found within the mitochondria of most ***(MagR)is a highly conserved A-type iron and iron-sulfur cluster-binding protein,characterized by two distinct types of iron-sulfur clusters,[2Fe-2S]and[3Fe-4S],each conferring unique magnetic *** forms a rod-like polymer structure in complex with photoreceptive cryptochrome(Cry)and serves as a putative magnetoreceptor for retrieving geomagnetic information in animal *** the N-terminal sequences of MagR vary among species,their specific function remains *** the present study,we found that the N-terminal sequences of pigeon MagR,previously thought to serve as a mitochondrial targeting signal(MTS),were not cleaved following mitochondrial entry but instead modulated the efficiency with which iron-sulfur clusters and irons are ***,the N-terminal region of MagR was required for the formation of a stable MagR/Cry ***,the N-terminal sequences in pigeon MagR fulfil more important functional roles than just mitochondrial *** results further extend our understanding of the function of MagR and provide new insights into the origin of magnetoreception from an evolutionary perspective.

关键词： Magnetoreceptor(MagR) N-terminal sequence Mitochondrial targeting signal Iron-sulfur cluster

Current status of early gastric cancer screening research

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cancer Biology & Medicine 2024年第3期21卷 218-222页

作者： can Hu Li Yuan Xiangdong Cheng Department of Gastric surgery Zhejiang Cancer HospitalHangzhou Institute of Medicine(HIM)Chinese Academy of SciencesHangzhouZhejiang 310022China Key Laboratory of Prevention Diagnosis and Therapy of Upper Gastrointestinal Cancer of Zhejiang ProvinceHangzhou 310022China Zhejiang Provincial Research Center for Upper Gastrointestinal Tract cancer Zhejiang Cancer HospitalHangzhou 310022China

Gastric cancer is a predominant threat to the health and well-being of China's residents. Data from the World Health Organization(WHO) in 2020 revealed that gastric cancer in China notably accounted for 44.0% of new c... 详细信息

关键词： cancer Gastric gastric

Time series analysis of L-band PALSAR-2 images in Istanbul and Kocaeli,Turkey

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Big Earth Data 2024年第3期8卷 467-493页

作者： Sadra Karimzadeh Abdullah can Zulfikar Masashi Matsuoka Department of Remote Sensing and GIS University of TabrizTabrizIran Department of Architecture and Building Engineering Tokyo Institute of TechnologyYokohamaJapan Disaster Management Institute Istanbul Technical UniversityMaslakIstanbulTurkey

ABSTRACT Conducting long measurements of infrastructure deformation is a critical engineering *** methods are both timeconsuming and expensive,limiting their use for large-scale *** synergy of synthetic aperture radar(SAR)and geographic information systems(GIS)offers a complementary *** study focuses on the feasibility of using time series analysis of L-band PALSAR-2 images to discover land displacements in Istanbul and Kocaeli,significant industrial and residential areas in ***-2 phase and intensity information were *** phase analysis,1. L-band images from 201. to 2021.were taken into *** baseline subset(SBAS)analysis was performed using 44 pairs,and results of the velocity,coherence and back-scattering values are *** of all pairs and their correlations were *** Component Analysis(PCA)reduced the dimension of coherence pairs,enhancing feature extraction and the final geocoded velocity map revealed a fastest subsidence rate of−58 mm/yr and a mean subsidence of−20 mm/*** findings were confirmed through mean vertical velocity from Sentinel-1.datasets and field *** results showed that immature land subsidence in the mentioned areas are growing slowly,which can be taken as a serious risk in future.

关键词： InSAR time series PALSAR-2 SAR intensity infrastructure deformation

NHC-derived carbon-centered luminescent radicals with shortwavelength emission via suppression of Kasha's rule

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Science China Chemistry 2024年第8期67卷 2679-2685页

作者： can Chen Xin Li Xinhua Ouyang Ying-Feng Han Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education Xi’an Key Laboratory of Functional Supramolecular Structure and MaterialsCollege of Chemistry and Materials ScienceNorthwest UniversityXi’an 710127China College of Material Engineering Fujian Agriculture and Forestry University Fuzhou 350108China

Luminescent organic radicals have garnered increasing attention owing to their versatile applications in sensing, imaging, and organic light-emitting diodes(OLEDs), attributed to their unique emission properties originating from the doublet spin ***, the natural narrow bandgap of organic free radicals typically limits their emission to the long-wavelength *** luminescent organic radicals with short-wavelength emission remains a significant challenge. Herein, a series of carbon-centered radicals with short-wavelength emission(383–476 nm) by combining N-heterocyclic carbenes with various polycyclic aromatic hydrocarbons(PAHs)(2-naphthyl, 2a~Ⅰ and 2b~Ⅰ;2-phenanthryl, 2a~Ⅱand 2b~Ⅱ;2-anthryl, 2a~Ⅲand 2b~Ⅲ;3-phenanthryl, 2a~Ⅳand 2b~Ⅳ). Theoretical calculations reveal that the introduction of PAHs significantly increases the ΔE_(D2-D1. in 2a^(Ⅰ–Ⅲ)and 2b^(Ⅰ–Ⅲ)compared to that in phenyl-derived radical congeners. Consequently, the internal transition from D2 to D1.is impeded, leading to a high yield of D2 emission and a suppressed Kasha's rule, thereby overcoming the limitations imposed by their narrow bandgap. For 2a~Ⅳ and 2b~Ⅳ, despite a moderately large ΔED2-D1.alue, the ΔED3-D1.alue exceeds 1.e V, indicating that their emission likely originates from the D3 state. Furthermore, we utilized 2a~Ⅲand 2b~Ⅲ as emissive materials in OLEDs,resulting in blue emissions with external quantum efficiencies of 7.5% and 6.5%, respectively.

关键词： N-heterocyclic carbenes luminescent organic molecules carbon-centered radicals short-wavelength emission

Regulatable Orthotropic 3D Hybrid Continuous Carbon Networks for Efficient Bi-Directional Thermal Conduction

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Nano-Micro Letters 2024年第10期16卷 136-148页

作者： Huitao Yu Lianqiang Peng can Chen Mengmeng Qin Wei Feng School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin 300350People's Republic of China

Vertically oriented carbon structures constructed from low-dimen-sional carbon materials are ideal frameworks for high-performance thermal inter-face materials(TIMs).However,improving the interfacial heat-transfer efficiency of vertically oriented carbon structures is a challenging ***,an orthotropic three-dimensional(3D)hybrid carbon network(VSCG)is fabricated by depositing vertically aligned carbon nanotubes(VACNTs)on the surface of a horizontally oriented graphene film(HOGF).The interfacial interaction between the VACNTs and HOGF is then optimized through an annealing *** regulating the orientation structure of the VACNTs and filling the VSCG with polydimethylsi-loxane(PDMS),VSCG/PDMS composites with excellent 3D thermal conductive properties are *** highest in-plane and through-plane thermal conduc-tivities of the composites are 1.3.61.and 24.37 W m^(-1.K^(-1.,*** high contact area of HOGF and good compressibility of VACNTs imbue the VSCG/PDMS composite with low thermal *** addition,the interfacial heat-transfer efficiency of VSCG/PDMS composite in the TIM performance was improved by 71.3%compared to that of a state-of-the-art thermal *** new structural design can potentially realize high-performance TIMs that meet the need for high thermal conductivity and low contact thermal resistance in interfacial heat-transfer processes.

关键词： Orthotropic continuous structures Hybrid carbon networks Carbon/polymer composites Thermal interface materials

Breaking the scattering limits of water waves

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National Science Review 2024年第6期11卷 85-86页

作者： Adrià canós Valero Thomas Weiss Yuri Kivshar Institute of Physics University of Graz 4th Physics Institute University of Stuttgart Research School of Physics Australian National University

When water, light or sound waves impinge on objects smaller than the wavelength, a scattering process takes place[1.. The scattering of waves plays an essential role in a myriad of natural phenomena. In ocean engineering, enhancing the scattering of water waves allows capturing energy from larger areas, with clear implications for energy harvesting and coastal protection.

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